A tax return emailed as a PDF attachment. A medical scan shared through a cloud link. A legal contract uploaded to a file sharing platform. These are the kinds of files people share every day without thinking about who else might be able to read them.

The uncomfortable truth: unless you are using end-to-end encryption, your “confidential” files may not be confidential at all.

The Risk Most People Overlook

When you upload a file to a standard cloud service, the provider encrypts it on their servers using keys they control. This protects against outside hackers to some degree — but the provider itself can access your data. So can:

• Employees with sufficient access privileges
• Law enforcement armed with a subpoena or warrant
• Hackers who breach the provider’s key management systems
• AI training pipelines that ingest user data (increasingly common with free services)

For casual files, this is acceptable. For confidential files, it is not.

What Makes a File “Confidential”

If a leak would cause financial harm, legal liability, reputational damage, or personal embarrassment, the file is confidential. Common examples:

File Type	Why It’s Confidential	Consequences of a Leak
Tax returns	Contains SSN, income, financial details	Identity theft, financial fraud
Medical records	Contains health conditions, treatments	Discrimination, privacy violation
Legal contracts	Contains terms, financial obligations	Competitive disadvantage, legal disputes
Business financials	Contains revenue, costs, margins	Competitor intelligence, investor concerns
Personal photos/videos	Contains private moments	Embarrassment, harassment, blackmail
Intellectual property	Contains unreleased creative work	Lost competitive advantage, piracy

How E2E Encryption Closes the Gap

With end-to-end encryption, confidential files are encrypted on your device before they leave it. The decryption key is shared only with the intended recipient — never with the cloud provider, never stored on a server.

This means:

• A server breach exposes only encrypted gibberish
• An employee at the provider cannot read your files even with full database access
• A government subpoena to the provider yields nothing useful — they do not have the keys
• AI training systems cannot ingest your file contents because they are encrypted

The provider becomes a secure storage locker that even they cannot open. Your confidential files remain confidential in the truest sense.

Practical Steps

1. Identify your confidential files — not everything needs E2E encryption, but anything meeting the criteria above does
2. Choose an E2E encrypted service — look for client-side encryption, zero-knowledge architecture, and documented cryptographic implementation
3. Verify the encryption is real — if the provider can preview your files or recover them after you lose access, they hold the keys (that is not E2E)
4. Share links securely — send download links through encrypted messaging (Signal, iMessage) rather than unencrypted email when possible
5. Delete after receipt — once the recipient confirms they have the file, remove it from the sharing service

Frequently Asked Questions

Is email safe enough for confidential files?

No. Standard email encrypts messages in transit (TLS) but stores them unencrypted on the mail server. Both the sender’s and recipient’s email providers can access attachments. For confidential files, use an E2E encrypted sharing service and send the link via email instead of the file itself.

Does Stash support end-to-end encryption for all file types?

Yes. Stash encrypts every file using AES-256-GCM regardless of type — documents, photos, videos, archives, and any other format. The encryption is applied at the file level before upload, and the key is embedded in the share link.

What if I accidentally share a confidential file without encryption?

Delete it from the sharing service immediately. If the file was accessed before deletion, you cannot un-share it, but you can limit further exposure. For highly sensitive leaks (SSN, medical records), consider credit monitoring or legal consultation depending on the content.